Intervertebral implant

ABSTRACT

An adjustable spinal fusion intervertebral implant is provided that can comprise upper and lower body portions that can each have proximal and distal wedge surf aces disposed at proximal and distal ends thereof. An actuator shaft disposed intermediate the upper and lower body portions can be actuated to cause proximal and distal protrusions to converge towards each other and contact the respective ones of the proximal and distal wedge surfaces. Such contact can thereby transfer the longitudinal movement of the proximal and distal protrusions against the proximal and distal wedge surfaces to cause the separation of the upper and lower body portions, thereby expanding the intervertebral implant. The upper and lower body portions can have side portions that help facilitate linear translational movement of the upper body portion relative to the lower body portion.

PRIORITY INFORMATION

The present application is a continuation application of U.S.application Ser. No. 16/243,188 filed Jan. 9, 2019, which is acontinuation application of U.S. application Ser. No. 13/845,644 filedMar. 18, 2013, which is a continuation of U.S. application Ser. No.13/334,526, filed Dec. 22, 2011 (now issued as U.S. Pat. No. 8,568,481),which is a continuation of U.S. application Ser. No. 11/952,900, filedDec. 7, 2007 (now issued as U.S. Pat. No. 8,105,382), which claims thepriority benefit of U.S. Provisional Application Ser. No. 60/869,088,filed Dec. 7, 2006. The entire contents of these applications are herebyincorporated by reference herein.

BACKGROUND Field of the Invention

The present invention relates to medical devices and, more particularly,to an intervertebral implant.

Description of the Related Art

The human spine is a flexible weight bearing column formed from aplurality of bones called vertebrae. There are thirty three vertebrae,which can be grouped into one of five regions (cervical, thoracic,lumbar, sacral, and coccygeal). Moving down the spine, there aregenerally seven cervical vertebra, twelve thoracic vertebra, five lumbarvertebra, five sacral vertebra, and four coccygeal vertebra. Thevertebra of the cervical, thoracic, and lumbar regions of the spine aretypically separate throughout the life of an individual. In contrast,the vertebra of the sacral and coccygeal regions in an adult are fusedto form two bones, the five sacral vertebra which form the sacrum andthe four coccygeal vertebra which form the coccyx.

In general, each vertebra contains an anterior, solid segment or bodyand a posterior segment or arch. The arch is generally formed of twopedicles and two laminae, supporting seven processes—four articular, twotransverse, and one spinous. There are exceptions to these generalcharacteristics of a vertebra. For example, the first cervical vertebra(atlas vertebra) has neither a body nor spinous process. In addition,the second cervical vertebra (axis vertebra) has an odontoid process,which is a strong, prominent process, shaped like a tooth, risingperpendicularly from the upper surface of the body of the axis vertebra.Further details regarding the construction of the spine may be found insuch common references as Gray's Anatomy, Crown Publishers, Inc., 1977,pp. 33-54, which is herein incorporated by reference.

The human vertebrae and associated connective elements are subjected toa variety of diseases and conditions which cause pain and disability.Among these diseases and conditions are spondylosis, spondylolisthesis,vertebral instability, spinal stenosis and degenerated, herniated, ordegenerated and herniated intervertebral discs. Additionally, thevertebrae and associated connective elements are subject to injuries,including fractures and torn ligaments and surgical manipulations,including laminectomies.

The pain and disability related to the diseases and conditions oftenresult from the displacement of all or part of a vertebra from theremainder of the vertebral column. Over the past two decades, a varietyof methods have been developed to restore the displaced vertebra totheir normal position and to fix them within the vertebral column.Spinal fusion is one such method. In spinal fusion, one or more of thevertebra of the spine are united together (“fused”) so that motion nolonger occurs between them. Thus, spinal fusion is the process by whichthe damaged disc is replaced and the spacing between the vertebrae isrestored, thereby eliminating the instability and removing the pressureon neurological elements that cause pain.

Spinal fusion can be accomplished by providing an intervertebral implantbetween adjacent vertebrae to recreate the natural intervertebralspacing between adjacent vertebrae. Once the implant is inserted intothe intervertebral space, osteogenic substances, such as autogenous bonegraft or bone allograft, can be strategically implanted adjacent theimplant to prompt bone ingrowth in the intervertebral space. The boneingrowth promotes long-term fixation of the adjacent vertebrae. Variousposterior fixation devices (e.g., fixation rods, screws etc.) can alsobe utilize to provide additional stabilization during the fusionprocess.

Recently, intervertebral implants have been developed that allow thesurgeon to adjust the height of the intervertebral implant. Thisprovides an ability to intra-operatively tailor the intervertebralimplant height to match the natural spacing between the vertebrae. Thisreduces the number of sizes that the hospital must keep on hand to matchthe variable anatomy of the patients.

In many of these adjustable intervertebral implants, the height of theintervertebral implant is adjusted by expanding an actuation mechanismthrough rotation of a member of the actuation mechanism. In someintervertebral implants, the actuation mechanism is a screw or threadedportion that is rotated in order to cause opposing plates of the implantto move apart. In other implants, the actuation mechanism is a helicalbody that is counter-rotated to cause the body to increase in diameterand expand thereby.

Furthermore, notwithstanding the variety of efforts in the prior artdescribed above, these intervertebral implants and techniques areassociated with another disadvantage. In particular, these techniquestypically involve an open surgical procedure, which results higher cost,lengthy in-patient hospital stays and the pain associated with openprocedures.

Therefore, there remains a need in the art for an improvedintervertebral implant. Preferably, the implant is implantable through aminimally invasive procedure. Further, such devices are preferably easyto implant and deploy in such a narrow space and opening while providingadjustability and responsiveness to the clinician.

SUMMARY OF THE INVENTION

Accordingly, one embodiment of the present invention comprises a spinalfusion intervertebral implant that includes upper and lower bodyportions and an actuator shaft that can be sized and configured to bereceived therebetween. The upper and lower body portions can each haveproximal surfaces disposed at proximal ends thereof. The actuator shaftcan comprise an inner member and an outer sleeve member adapted to betranslatable relative to the inner member. The inner member can havedistal and proximal ends and at least one retention structure disposedtherebetween. The outer sleeve member can have a proximal end and atleast one complementary retention structure being sized and configuredto engage the retention structure of the inner member to facilitateselective relative movement of the proximal end of the outer sleevemember toward the distal end of the inner member without rotation.

Further, the intervertebral implant can also include at least oneproximal wedge member which can be disposed at the proximal end of theouter sleeve member. The proximal protrusion can be sized and configuredto contact the proximal surfaces of the upper and lower body portionsupon selective relative movement of the proximal end of the outer sleevemember toward the distal end of the inner member. The longitudinalmovement of the proximal wedge member against the proximal surfaces cancause the separation of the upper and lower body portions.

In accordance with another embodiment, a spinal fusion intervertebralimplant is provided that comprises upper and lower body portions eachhaving proximal and distal surfaces at proximal and distal ends thereof.The proximal and distal surfaces of the upper and lower body portionscan be configured to generally face each other. The implant can furthercomprise an actuator shaft received between the upper and lower bodyportions. The actuator shaft can comprise an inner member and an outersleeve member selectively moveable relative to the inner member. Theimplant can further comprise a distal wedge member disposed at a distalend of the inner member. The distal wedge member can have an engagementsurface configured to provide ratchet-type engagement with the distalsurfaces of the upper and lower body portions upon selective relativemovement of the distal end of the inner member toward the proximal endof the outer sleeve member. Further, the implant can comprise a proximalwedge member disposed at a proximal end of the outer sleeve member. Theproximal wedge member can have an engagement surface configured toprovide ratchet-type engagement with the proximal surfaces of the upperand lower body portions upon selective relative movement of the proximalend of the outer sleeve member toward the distal end of the innermember. In such an embodiment, longitudinal movement of the distal wedgemember against the distal surfaces and the longitudinal movement of theproximal wedge member against the proximal surfaces can cause separationof the upper and lower body portions. Furthermore, the ratchet-typeengagement between the distal and proximal wedge members and therespective ones of the proximal and distal surfaces of the upper andlower body portions can maintain separation of the upper and lower bodyportions.

In accordance with yet another embodiment, a method of implanting aimplant is also provided. The method can comprise the steps ofpositioning the implant between two vertebral bodies and moving an innermember of an actuator shaft of the implant in an proximal directionrelative to an outer sleeve member disposed about the inner sleevemember to force a proximal protrusion of the outer sleeve member againstproximal surfaces of respective ones of upper and lower body portions ofthe implant to separate the upper and lower body portions to cause theimplant to expand intermediate the vertebral bodies.

In accordance with yet another embodiment, a method of implanting aimplant is also provided. The method can comprise the steps ofpositioning the implant between two vertebral bodies and rotating ascrew mechanism of the implant to cause proximal and distal wedgemembers to converge toward each other and engage respective ones ofproximal and distal surfaces of upper and lower body portions of theimplant to separate the upper and lower body portions to cause theimplant to expand.

In accordance with yet another embodiment, an adjustable spinal fusionintervertebral implant is provided that comprises upper and lower bodyportions, proximal and distal wedge members, and a pin.

The upper and lower body portions can each have proximal and distalsurfaces at proximal and distal ends thereof. The proximal and distalsurfaces of the upper and lower body portions can generally face eachother. The proximal surfaces of the respective ones of the upper andlower body portions can each define a proximal slot therein. The distalsurfaces of the respective ones of the upper and lower body portions caneach define a distal slot therein.

The proximal wedge member can be disposed at the proximal ends of therespective ones of the upper and lower body portions. The proximal wedgemember can comprise upper and lower guide members extending at leastpartially into the respective ones of the proximal slots of the upperand lower body portions with at least a portion of the proximal wedgemember contacting the proximal surfaces of the upper and lower bodyportions. The distal wedge member can be disposed at the distal ends ofthe respective ones of the upper and lower body portions. The distalwedge member can comprise upper and lower guide members extending atleast partially into the respective ones of the distal slots of theupper and lower body portions with at least a portion of the distalwedge member contacting the distal surfaces of the upper and lower bodyportions.

The actuator shaft can be received between the upper and lower bodyportions. The actuator shaft can extend intermediate the distal andproximal wedge members, wherein rotation of the actuator shaft causesthe distal and proximal wedge members to be drawn together such thatlongitudinal movement of the distal wedge member against the distalsurfaces and the longitudinal movement of the proximal wedge memberagainst the proximal surfaces causes separation of the upper and lowerbody portions.

In such an embodiment, the upper body portion can further comprise apair of downwardly extending side members and the lower body portionfurther comprises a pair of upwardly extending side members. The sidemembers of the upper body portion can engage the side members of thelower body portion to facilitate linear translational movement of theupper body portion relative to the lower body portion. The side membersof the upper body portion can each comprise a slot and the side membersof the lower body portion each comprise a guide member. The guidemembers of the side members of the lower body portion can each bereceived into the slots of the side members of the upper body portion.

The implant can be configured wherein the proximal and distal surfacesof the upper and lower body portions are sloped. The slots of theproximal and distal surfaces of the upper and lower body portions canalso be sloped. Further, the slots of the proximal and distal surfacesof the upper and lower body portions can be generally parallel to therespective proximal and distal surfaces of the upper and lower bodyportions. In other embodiments, the slots of the proximal and distalsurfaces of the upper and lower body portions can be generallydove-tailed. The guide members of the proximal and distal wedge memberscan also be generally dovetailed. In other embodiments, the upper andlower body portions can comprise generally arcuate respective upper andlower exterior engagement surfaces.

The proximal wedge member can comprise an anti-rotational element. Theanti-rotational engagement can be configured to be engaged by an implanttool for preventing rotation of the implant when the actuator shaft isrotated relative to the implant. The anti-rotational element cancomprise a pair of apertures extending into the proximal wedge member.

In yet another embodiment, an implantation tool is provided forimplanting an expandable intervertebral implant. The tool can comprise ahandle section, a distal engagement section, and an anti-rotationalengagement member. The handle section can comprise a fixed section andfirst and second rotatable members. The distal engagement section cancomprise a fixed portion and first and second rotatable portions beingoperatively coupled to the respective ones of the first and secondrotatable members. The first rotatable portion can comprise a distalattachment element. The distal engagement element can be operative to beremovably attached to a distal end of at least a portion of the implant.The second rotatable portion can comprise a distal engagement memberbeing configured to engage a proximal end of an actuator shaft of theimplant for rotating the actuator shaft to thereby and expanding theimplant from an unexpanded state to and expanded state. Theanti-rotational engagement member can be used to engage ananti-rotational element of the implant.

In some embodiments, the first and second rotatable members of the toolcan be coaxially aligned. Further, the first and second rotatableportions can be coaxially aligned. The first and second rotatableportions can be tubular, and the first rotatable portion can be disposedinternally to the second rotatable portion. The fixed portion of thedistal engagement section can be tubular and the first and secondrotatable portions can be disposed internally to the fixed portion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of an intervertebral implant in an unexpandedstate while positioned intermediate adjacent vertebrae, according to anembodiment.

FIG. 2 is a side view of the intervertebral implant shown in FIG. 1 inan expanded state.

FIG. 3 is a perspective view of the intervertebral implant shown in FIG.1 in an unexpanded state.

FIG. 4 is a perspective view of the intervertebral implant shown in FIG.3 in an expanded state.

FIG. 5 is a side cross sectional view of the intervertebral implantshown in FIG. 3 in an unexpanded state.

FIG. 6 is a side cross-sectional view of the intervertebral implantshown in FIG. 5 in an expanded state.

FIG. 7 is a side cross-sectional view of the intervertebral implantshown in FIG. 5 in an expanded state and wherein a portion of anactuator shaft has been removed.

FIG. 8 is a side cross sectional view of another embodiment of theactuator shaft of the intervertebral implant shown in FIG. 3 , whereinthe actuator shaft has an outer sleeve member and an inner sleevemember.

FIG. 9A is a side perspective view of a portion of a modified embodimentof the outer sleeve member.

FIG. 9B is an enlarged longitudinal cross-sectional view of a modifiedembodiment of the outer sleeve member with the portion shown in FIG. 9A.

FIG. 9C is a perspective view of another embodiment of an outer sleevemember.

FIGS. 9D and 9E are enlarged views of a portion of one embodiment of anouter sleeve member.

FIG. 9F is a front view of the outer sleeve member shown in FIG. 9C.

FIG. 10A is a side cross sectional view of another embodiment of anintervertebral implant.

FIG. 10B is an enlarged view of the section 10B shown in FIG. 10A.

FIG. 11 is a side cross-sectional view of another embodiment of anactuator shaft of the intervertebral implant shown in FIG. 10A.

FIG. 12 is a perspective view of the embodiment of the intervertebralimplant shown in FIG. 10A in an unexpanded state.

FIG. 13 is a perspective view of the embodiment of the intervertebralimplant shown in FIG. 10A in an expanded state.

FIG. 14A is a side view of another embodiment of the intervertebralimplant wherein the upper and lower body portions have generally slantedconfigurations.

FIG. 14B is a top view of another embodiment of the intervertebralimplant wherein the upper and lower body portions have semicircularupper and lower faces.

FIG. 14C is a top view of another embodiment of the intervertebralimplant wherein the upper and lower body portions have generally squareupper and lower faces.

FIG. 14D is a top view illustrating an embodiment of an application ofthe intervertebral implant utilizing a plurality of intervertebralimplants disposed in an intervertebral space to support adjacentvertebrae.

FIG. 15 is a side cross-sectional view of another embodiment of theintervertebral implant wherein rotational movement can be utilized toexpand the implant.

FIG. 16A is a perspective view of another embodiment of anintervertebral implant in an unexpanded state.

FIG. 16B is a perspective view of the intervertebral implant shown inFIG. 16A wherein the implant is in an expanded state.

FIG. 17 is a bottom view of the intervertebral implant shown in FIG.16A.

FIG. 18 is a side view of the intervertebral implant shown in FIG. 16B.

FIG. 19 is a front cross-sectional view of the intervertebral implantshown in FIG. 16B taken along lines 19-19.

FIG. 20A is a bottom perspective view of a lower body portion of theintervertebral implant shown in FIG. 16A.

FIG. 20B is a top perspective view of the lower body portion of theintervertebral implant shown in FIG. 16A.

FIG. 21A is a bottom perspective view of an upper body portion of theintervertebral implant shown in FIG. 16A.

FIG. 21B is a top perspective view of the upper body portion of theintervertebral implant shown in FIG. 16A.

FIG. 22 is a perspective view of an actuator shaft of the intervertebralimplant shown in FIG. 16A.

FIG. 23A is a front perspective view of a proximal wedge member of theintervertebral implant shown in FIG. 16A.

FIG. 23B is a rear perspective view of the proximal wedge member of theintervertebral implant shown in FIG. 16A.

FIG. 24A is a front perspective view of a distal wedge member of theintervertebral implant shown in FIG. 16A.

FIG. 24B is a rear perspective view of the distal wedge member of theintervertebral implant shown in FIG. 16A.

FIG. 25 is a perspective view of a deployment tool according to anembodiment.

FIG. 26 is a side cross-sectional view of the deployment tool shown inFIG. 25 wherein an expandable implant is attached to a distal endthereof.

DETAILED DESCRIPTION

In accordance with certain embodiments disclosed herein, an improvedintervertebral implant is provided that allows the clinician to insertthe intervertebral implant through a minimally invasive procedure. Forexample, in one embodiment, one or more intervertebral implants can beinserted percutaneously to reduce trauma to the patient and therebyenhance recovery and improve overall results of the surgery.

For example, in one embodiment, an intervertebral implant includes aplurality of body sections that are selectively separable and expandableupon contraction of a centrally disposed actuator. The actuator can beutilized to contract against faces of the body sections to cause theexpansion thereof. The implant can also be configured such that theactuator provides for both the expansion and contraction of the bodysections. The actuator can comprise an interaction between the bodysections and another element, an action performed by another element, ora combination of interactions between various elements of the implantand its body sections. Further, the implant can be configured to alloweither rough or fine incremental adjustments in the expansion of theimplant.

The embodiments disclosed herein are discussed in the context of anintervertebral implant and spinal fusion because of the applicabilityand usefulness in such a field. As such, various embodiments can be usedto properly space adjacent vertebrae in situations where a disc hasruptured or otherwise been damaged. As also disclosed herein,embodiments can also be used as vertebral body replacements. Thus,“adjacent” vertebrae can include those originally separated only by adisc or those that are separated by intermediate vertebra and discs.Such embodiments can therefore tend to recreate proper disc height andspinal curvature as required in order to restore normal anatomicallocations and distances. However, it is contemplated that the teachingsand embodiments disclosed herein can be beneficially implemented in avariety of other operational settings, for spinal surgery and otherwise.

For example, the implant disclosed herein can also be used as avertebral body replacement. In such a use, the implant could be used asa replacement for a lumbar vertebra, such as one of the L1-L5 vertebrae.Thus, the implant could be appropriately sized and configured to be usedintermediate adjacent vertebrae, or to entirely replace a damagedvertebra.

It is contemplated that the implant can be used as an interbody orintervertebral device or can be used to replace a vertebral bodyentirely. The implant can also be used in vertebral body compressionfractures. Further, the implant can be used as a tool to expand anintervertebral space or bone in order to fill the space or bone with acement; in such cases, the implant can be removed or left in once thecement is placed. Furthermore, the implant can also be used as a tool topredilate disc space. In some embodiments, the implant can be removedonce the disc space is dilated, and a different implant (expandable ornon-expandable) can then be implanted in the dilated disc space.Finally, the implant can also be introduced into the disc spaceanteriorly in an anterior lumbar interbody fusion (ALIF) procedure,posterior in an posterior lumbar interbody fusion (PILF) or posteriallateral interbody fusion, from extreme lateral position in an extremelateral interbody fusion procedure, and transforaminal lumbar interbodyfusion (TLIF), to name a few. Although the implant is primarilydescribed herein as being used to expand in a vertical direction, it canalso be implanted to expand in a horizontal direction in order toincrease stability and/or increase surface area between adjacentvertebral bodies.

Additionally, the implant can comprise one or more height changemechanisms to facilitate expansion of the implant. For example, theimplant can use a classic wedge system, a parallel bar and linkagesystem, a jack system, a pair of inclined planes, a screw jack system, acam system, a balloon and bellows system, a hydraulic or pneumaticsystem, a longitudinal deformation/crush system (in which longitudinalcontraction creates vertical expansion), or a stacking system, to name afew. Furthermore, the implant can comprise one or more height retentionmechanisms. For example, the implant can use a pin ratchet system, awedge ratchet system, a lead screw system with left or right-handthreads, or a lead screw system with left and right-hand threads, toname a few.

Therefore, it is contemplated that a number of advantages can berealized utilizing various embodiments disclosed herein. For example, aswill be apparent from the disclosure, no external distraction of thespine is necessary. Further, no distraction device is required in orderto install various embodiments disclosed herein. In this regard,embodiments of the implant can enable sufficient distraction of adjacentvertebra in order to properly restore disc height or to use the implantas a vertebral body replacement. Thus, normal anatomical locations,positions, and distances can be restored and preserved utilizing many ofthe embodiments disclosed herein.

Referring to FIG. 1 , there is illustrated a side view of an embodimentof a intervertebral implant 10 in an unexpanded state while positionedgenerally between adjacent vertebrae of the lumbar portion of the spine12. FIG. 2 illustrates the intervertebral implant 10 in an expandedstate, thereby supporting the vertebrae in a desired orientation andspacing in preparation for spinal fusion. As is known in the art, spinalfusion is the process by which the adjacent vertebrae of the spine areunited together (“fused”) so that motion no longer occurs between thevertebrae. Thus, the intervertebral implant 10 can be used to providethe proper spacing two vertebrae to each other pending the healing of afusion. See also U.S. Patent Publication No. 2004/0127906, filed Jul.18, 2003, application Ser. No. 10/623,193, the entirety of thedisclosure of which is hereby incorporated by reference.

According to an embodiment, the implant can be installed in an operationthat generally entails the following procedures. The damaged disc orvertebra can be decompressed, such as by distracting. The subjectportion (or entire) disc or vertebra can then be removed. The adjacentvertebrae can be prepared by scraping the exposed adjacent portion orplates thereof (typically to facilitate bleeding and circulation in thearea). Typically, most of the nucleus of the disc is removed and theannulus of the disc is thinned out. Although individual circumstancesmay vary, it may be unusual to remove all of the annulus or to perform acomplete discectomy. The implant can then be installed. In someembodiments, distraction of the disc may not be a separate step fromplacement of the implant; thus, distraction can be accomplished and canoccur during placement of the implant. Finally, after implantation ofthe implant, osteogenic substances, such as autogenous bone graft, boneallograft, autograft foam, or bone morphogenic protein (BMP) can bestrategically implanted adjacent the implant to prompt bone ingrowth inthe intervertebral space. In this regard, as the implant is expanded,the spaces within the implant can be backfilled; otherwise, the implantcan be prepacked with biologics.

The intervertebral implant is often used in combination with posteriorand/or anterior fixation devices (e.g., rods, plates, screws, etc. thatspan two or more vertebrae) to limit movement during the fusion process.U.S. Patent Publication No. 2004/0127906 discloses a particularlyadvantageous posterior fixation device and method which secures twoadjacent vertebra to each other in a trans-laminar, trans-facet orfacet-pedicle (e.g., the Boucher technique) application using fixationscrews.

It should also be appreciated that in FIGS. 1 and 2 only oneintervertebral implant 10 is shown positioned between the vertebrae 12.However, as will be discussed in more detail below, it is anticipatedthat two, three or more implants 10 can be inserted into the spacebetween the vertebrae. Further, other devices, such as bone screws, canbe used on the vertebrae as desired. For example, in a spinal fusionprocedure, it is contemplated that one or more implants 10 can be usedin conjunction with one or more bone screws and/or dynamic stabilizationdevices, such as those disclosed in the above-mentioned U.S. PatentPublication No. 2004/0127906, filed Jul. 18, 2003, application Ser. No.10/623,193.

In another embodiment of use, the implant 10 can be used in combinationwith a dynamic stabilization devices such as those disclosed in U.S.Patent Publication No. 2006-0122609, filed Feb. 11, 2005, applicationSer. No. 11/056,991; U.S. Patent Publication No. 2005/0033289, filed onMay 6, 2004, now U.S. Pat. No. 6,951,561; U.S. Provisional PatentApplication No. 60/942,998, filed on Jun. 8, 2007; U.S. ProvisionalApplication No. 60/397,588 filed Jul. 19, 2002; U.S. ProvisionalApplication No. 60/424,055, filed Nov. 5, 2002; Ser. No. 10/623,193;U.S. Provisional Application No. 60/397,588 filed Jul. 19, 2002 andProvisional Application 60/424,055 filed Nov. 5, 2002; the entireties ofthe disclosures of which are hereby incorporated by reference. In thismanner, the implant 10 can be used to maintain height between vertebralbodies while the dynamic stabilization device provides limits in one ormore degrees of movement.

The embodiment of the intervertebral implant 10 shown FIGS. 1 and 2 willnow be described in more detail with reference FIGS. 3 and 4 . FIG. 3illustrates a perspective view the intervertebral implant 10 in anunexpanded state while FIG. 4 illustrates the intervertebral implant 10in an expanded state. The intervertebral implant 10 can comprise anupper body portion 14 and a lower body portion 16. The upper and lowerbody portions 14, 16 can each have a proximally facing surface 18, 20disposed at respective proximal ends 22, 24 thereof and generally facingeach other. As will be explained below, the proximally facing surfaces18, 20 can be inclined or otherwise curved with respect to thelongitudinal axis of the body portions 14, 16.

In the illustrated embodiment, the upper and lower body portions 14, 16are illustrated as being configured substantially as parallel plate likestructures. As will be explained below, the upper and lower bodyportions 14, 16 can be variously configured and designed, such as beinggenerally ovular, wedge-shaped, and other shapes. For example, insteadof including smooth exterior surfaces, as shown, the upper and lowerbody portions 14, 16 can be configured to include a surface texture,such as one or more external teeth, in order to ensure that theintervertebral implant 10 is maintained in a given lateral position onceexpanded intermediate the adjacent vertebrae of the spine 12. Other suchmodifications can be implemented in embodiments disclosed herein, andmay be readily understood by one of skill in the art.

The intervertebral implant 10 can further comprise an actuator shaft 30that can be sized and configured to be received between the upper andlower body portions 14, 16. As described herein with respect to variousembodiments, the actuator shaft 30 can be utilized not only to move theintervertebral implant 10 from the unexpanded to the expanded state, butalso to maintain expansion of the intervertebral implant 10. Theactuator shaft 30 can be utilized in several embodiments to providenumerous advantages, such as facilitating precise placement, access, andrapid deployment of the intervertebral implant 10.

As shown in FIGS. 5 and 6 , the actuator shaft 30 can comprise an innermember 32 and an outer sleeve member 34. In accordance with anembodiment, the outer sleeve member 34 can be adapted to be translatablerelative to the inner member 32 such that the distance between thedistal end of the inner member 32 and the proximal end of the outermember 34 can be reduced or shortened. The inner member 32 can have adistal end 36, a proximal end 38, and at least one retention structure40 disposed therebetween. The outer sleeve member 32 can also have aproximal end 42 and at least one complementary retention structure 44.

In general, the retention structures 40, 44 between the inner member 32and the outer member 34 can be configured such that facilitate selectiverelative movement of the proximal end 42 of the outer sleeve member 34with respect to the distal end 36 of the inner member 32. Whilepermitting such selective relative movement, the structures 40, 44 arepreferably configured to resist movement once the distance between theproximal end 42 of the outer sleeve member 34 with respect to the distalend 36 of the inner member 32 is set. As will be described below, theretention structures 40, 44 can comprise any of a variety threads orscrew-like structures, ridges, ramps, and/or ratchet type mechanismswhich those of skill in the art will recognize provide such movement.

In some embodiments, the movement of proximal end 42 of the outer sleevemember 34, which may be in a direction distal to the clinician, can beaccomplished without rotation of the actuator shaft 30, or any portionthereof. Thus, some embodiments provide that the actuator shaft 30 canbe advantageously moved to the engaged position using only substantiallylongitudinal movement along an axis of the actuator shaft 30. It iscontemplated that this axial translation of the outer sleeve member 34can aid the clinician and eliminate cumbersome movements such asrotation, clamping, or otherwise. In this regard, the clinician caninsert, place, and deploy the intervertebral implant 10 percutaneously,reducing the size of any incision in the patient, and thereby improvingrecovery time, scarring, and the like. These, and other benefits aredisclosed herein.

In accordance with another embodiment, the proximal end 38 of theactuator shaft 30 can also be provided with a structure 48 forpermitting releasable engagement with an installation or a removal tool50. The actuator shaft 30 can therefore be moved as required and thetool 50 can later be removed in order to eliminate any substantialprotrusions from the intervertebral implant 10. This feature can allowthe intervertebral implant 10 to have a discreet profile once implantedinto the patient and thereby facilitate healing and bone growth, whileproviding the clinician with optimal control and use of theintervertebral implant 10.

For example, as shown in FIG. 5 , structure 48 comprises interactingthreads between the distal end of the tool 50 and the proximal end 38 ofthe inner member 32. In a modified embodiment, the structure 48 cancomprise any of a variety of fixation devices (e.g., hooks, latches,threads, etc.) as will be apparent to those of skill in the art. Theactuator shaft 30 can therefore be securely coupled to the tool 50during implantation of the intervertebral implant 10. Once disposed inthe intervertebral space, the clinician can grasp the tool 50 tomaintain the inner member 32 of the actuator shaft 30 at a constantposition while pushing the outer sleeve member 34 in the distaldirection and/or pull on the tool to proximally retract the inner member32 while maintaining the outer member 34 stationary. Thus, the cliniciancan effectuate movement of the actuator shaft 30 and/or apply a forcethe actuator shaft 30. As will be described further below, this movementcan thereby cause the intervertebral implant 10 to move from theunexpanded to the expanded state.

Alternatively, the tool 50 can be omitted and/or combined with theactuator shaft 30 such that the actuator shaft 30 includes a proximalportion that extends proximally in order to allow the clinician tomanipulate the actuator shaft 30 position, as described with respect tothe tool 50. In such an embodiment, the actuator shaft 30 can beprovided with a first break point to facilitate breaking a proximalportion of the actuator shaft 30 which projects proximally of theproximal end 42 of the outer sleeve member 34 following tensioning ofthe actuator shaft 30 and expansion of the intervertebral implant 10.The break point can comprise an annular recess or groove, which canprovide a designed failure point if lateral force is applied to theproximal portion while the remainder of the attachment system isrelatively securely fixed in the intervertebral space. At least a secondbreak point can also be provided, depending upon the axial range oftravel of the outer sleeve member 34 with respect to the inner member32. Other features and embodiments can be implemented as described inU.S. Pat. No. 6,951,561, the disclosure of which is hereby incorporatedby reference in its entirety.

The retention structures 40, 44 of the inner member 32 and the outersleeve member 34 can thus permit proximal movement of the inner member32 with respect to the outer sleeve member 34 but resist distal movementof the inner member 32 with respect to the outer sleeve member 34. Asthe outer sleeve member 34 moves in the distal direction, thecomplementary retention structures 44 can engage the retentionstructures 40 of the inner member 32 to allow advancement of the outersleeve member 34 in a distal direction with respect to inner member 32,but which resist proximal motion of outer sleeve member with respect toinner member 32. This can result in one-way or ratchet-type movement.Thus, in such an embodiment, at least one of the complementary retentionstructures 44 and the retention structures can comprise a plurality ofannular rings, ramps, or ratchet-type structures. As mentioned above,any of a variety of ratchet-type structures can be utilized.

The actuator shaft 30 can also be configured to include a noncircularcross section or to have a rotational link such as an axially-extendingspline on the inner member 32 for cooperating with a complementarykeyway on the outer sleeve member 34. In another embodiment, theretention structures 40, 44 can be provided on less than the entirecircumference of the inner member 32 or outer sleeve member 34, as willbe appreciated by those of skill in the art. Thus, ratchet structurescan be aligned in an axial strip such as at the bottom of an axiallyextending channel in the surface of the inner member 32. In this manner,the outer sleeve member 34 can be rotated to a first position to bypassthe retention structures 40, 44 during axial advancement and thenrotated to a second position to engage the retention structures 40, 44.

In accordance with another embodiment, the retention structures 40 ofthe inner member 32 can comprise a plurality of threads, adapted tocooperate with the complimentary retention structures 44 on the outersleeve member 34, which may be a complimentary plurality of threads. Insuch an embodiment, the outer sleeve member 34 can be distally advancedalong the inner member 32 by rotation of the outer sleeve member 34 withrespect to the inner member 32, thus causing expansion of theintervertebral implant 10. The outer sleeve member 34 can alsoadvantageously be removed from the inner member 32 by reverse rotation,such as to permit contraction of the intervertebral implant 10 to theunexpanded state in order to adjust the position thereof within theintervertebral space or to facilitate the removal of the intervertebralimplant 10 from the patient.

For such a purpose, the outer sleeve member 34 can be preferablyprovided with a gripping configuration, structure, or collar 52 (seee.g., FIG. 7 ) to permit a removal instrument to rotate the outer sleevemember 34 with respect to the inner member 32. For example, such aninstrument can be concentrically placed about the tool 50 and engage thecollar 52. Thus, while holding the tool 50 in a fixed position, theclinician can reverse rotate the instrument to move the outer sleevemember 34 in a proximal direction. Any of a variety of grippingconfigurations may be provided, such as one or more slots, flats, bores,or the like. In the illustrated embodiment, the collar 52 can beprovided with a polygonal, and in particular, a hexagonal circumference,as seen in FIGS. 7 and 8 .

Various embodiments and/or additional or alternative components of theactuator shaft 30 and the retention structures 40, 44 can be found inU.S. Patent Publication 2004/0127906 (U.S. patent application Ser. No.10/623,193, filed Jul. 18, 2003) entitled “METHOD AND APPARATUS FORSPINAL FUSION”, which is hereby incorporated by reference. Additionalembodiments and/or alternative components of the actuator shaft 30 canbe found in U.S. patent application Ser. No. 60/794,171, filed on Apr.21, 2006, U.S. Pat. Nos. 6,951,561, 6,942,668, 6,908,465, and 6,890,333,which are also incorporated by reference. For example, as described inU.S. Pat. No. 6,951,561, the actuator shaft 30 can be configured withparticular spacing between the retention structures 40, 44; the actuatorshaft 30 dimensions, such as diameter and cross-section, can bevariously configured; and the actuator shaft 30 can be manufactured ofvarious types of materials.

FIGS. 9A and 9B illustrate a portion of a modified embodiment of anouter sleeve member and inner member that is similar to the embodimentsdescribed above. In this embodiment, the outer sleeve member preferablyincludes a recess 54 configured to receive an annular ring 55. In anembodiment, the annular ring 55 can be a split ring (i.e., having aleast one gap) and can be interposed between the inner member 32 and theproximal recess 54 of the outer sleeve member. In another embodiment,the ring 55 can be formed from an elastic material configured to ratchetover and engage with the inner member 32. In the split ring embodiment,the ring 55 comprises a tubular housing 56 that may be configured toengage with the inner member 32 and defines a gap or space 57. In oneembodiment, the gap 57 is defined by a pair of edges 58, 59. The edges58, 59 can be generally straight and parallel to each other. However,the edges 58, 59 can have any other suitable configuration andorientation.

For example, in one embodiment, the edges 58, 59 are curved and at anangle to each other. Although not illustrated, it should be appreciatedthat in modified embodiments, the ring 55 can be formed without a gap.When the ring 55 is positioned along the inner member 32, the ring 55preferably surrounds a substantial portion of the inner member 32. Thering 55 can be sized so that the ring 55 can flex or move radiallyoutwardly in response to an axial force so that the ring 55 can be movedrelative to the inner member 32. In one embodiment, the tubular housing56 includes at least one and in the illustrated embodiment four teeth orflanges 60, which are configured to engage the retention structures 40on the inner member 32. In the illustrated embodiment, the teeth orflanges include a first surface that generally faces the proximaldirection and is inclined with respect to the longitudinal axis of theouter sleeve member and a second surface that faces distal direction andlies generally perpendicular to the longitudinal axis of the outersleeve member. It is contemplated that the teeth or flanges 60 can haveany suitable configuration for engaging with the retention structures 40of the inner member 32.

As with the previous embodiment, the outer sleeve member can includesthe annular recess 54 in which the annular ring 55 may be positioned.The body 56 of the ring 55 can be sized to prevent substantial axialmovement between the ring 55 and the annular recess 54 (FIG. 9B) duringuse of the outer sleeve member. In one embodiment, the width of theannular recess 54 in the axial direction is slightly greater than thewidth of the annular ring 55 in the axial direction. This tolerancebetween the annular recess 54 and the annular ring 55 can inhibit, orprevent, oblique twisting of the annular ring 55 so that the body 56 ofthe ring 55 is generally parallel to the outer surface of the innermember 32.

Further, the recess 54 can be sized and dimensioned such that as theouter sleeve member is advanced distally over the inner member 32, theannular ring 55 can slide along the first surface and over thecomplementary retention structures 40 of the inner member 32. That is,the recess 54 can provide a space for the annular ring 55 to moveradially away from the inner member 32 as the outer sleeve member isadvanced distally. Of course, the annular ring 55 can be sized anddimensioned such that the ring 55 is biased inwardly to engage theretention structures 40 on the inner member 32. The bias of the annularring 55 can result in effective engagement between the flanges 60 andthe retention structures 40.

A distal portion 61 of the recess 54 can be sized and dimensioned suchthat after the outer sleeve member 53 is appropriately tensioned theannular ring 55 becomes wedged between the inner member 32 and an angledengagement surface of the distal portion 61. In this manner, proximalmovement of the outer sleeve member 53 can be prevented.

FIGS. 9C-9F illustrate another embodiment of an outer sleeve member 53′.In this embodiment, the outer sleeve member 53′ includes a recess 54configured to receive a split ring 55, as described above with referenceto FIGS. 9A and 9B. As will be explained in detail below, the outersleeve member 53′ can include an anti-rotation feature to limit orprevent rotation of the ring 55 within the outer sleeve member 53. Inlight of the disclosure herein, those of skill in the art will recognizevarious different configurations for limiting the rotation of the ring55. However, a particularly advantageous arrangement will be describedbelow with reference to the illustrated embodiment.

In the illustrated embodiment, the outer sleeve member 53′ has a tubularhousing 62 that can engage with the inner member 32 or the tool 50, asdescribed above. With reference to FIGS. 9D and 9F, the tubular housing62 can comprise one or more anti-rotational features 63 in the form of aplurality of flat sides that are configured to mate correspondinganti-rotational features 64 or flat sides of the inner member 32 of theactuator shaft 30. As shown in FIG. 9F, in the illustrated embodiment,the inner member 32 has three flat sides 64. Disposed between the flatsides 64 are the portions of the inner member 32 which include thecomplementary locking structures such as threads or ratchet likestructures as described above. The complementary locking structuresinteract with the ring 55 as described above to resist proximal movementof the outer sleeve member 53′ under normal use conditions whilepermitting distal movement of the outer sleeve member 53′ over the innermember 32.

As mentioned above, the ring 55 can be is positioned within the recess54. In the illustrated embodiment, the recess 54 and ring 55 arepositioned near to and proximal of the anti-rotational features 63.However, the ring 55 can be located at any suitable position along thetubular housing 62 such that the ring 55 can interact with the retentionfeatures of the inner member 32.

During operation, the ring 55 may rotate to a position such that the gap57 between the ends 58, 59 of the ring 55 lies above the complementaryretention structures on the inner member 32. When the ring 55 is in thisposition, there is a reduced contact area between the split ring 55 thecomplementary retention structures thereby reducing the locking strengthbetween the outer sleeve member 53′ and the inner member 32. In theillustrated embodiment, for example, the locking strength may be reducedby about ⅓ when the gap 57 over the complementary retention structuresbetween flat sides 64. As such, it is advantageous to position the gap57 on the flat sides 64 of the inner member 32 that do not includecomplementary retention structures.

To achieve this goal, the illustrated embodiment includes a pair of tabs65, 66 that extend radially inward from the interior of the outer sleevemember 53′. The tabs 65, 66 are configured to limit or preventrotational movement of the ring 55 relative to the housing 62 of theouter sleeve member 53′. In this manner, the gap 57 of the ring 55 maybe positioned over the flattened sides 64 of the inner member 32.

In the illustrated embodiment, the tabs 65, 66 have a generallyrectangular shape and have a generally uniform thickness. However, it iscontemplated that the tabs 65, 66 can be square, curved, or any othersuitable shape for engaging with the ring 55 as described herein.

In the illustrated embodiment, the tabs 65, 66 can be formed by makingan H-shaped cut 67 in the tubular housing 62 and bending the tabs 65, 66inwardly as shown in FIG. 9F. As shown in FIG. 9F, the tabs 65, 66(illustrated in phantom) are interposed between the edges 58, 59 of thering 55. The edges 58, 59 of the ring 55 can contact the tabs to limitthe rotational movement of the ring 55. Those skilled in the art willrecognize that there are many suitable manners for forming the tabs 65,66. In addition, in other embodiments, the tabs 65, 66 may be replacedby a one or more elements or protrusions attached to or formed on theinterior of the outer sleeve member 53′.

Referring again to FIGS. 3-6 , the actuator shaft 30 can also compriseat least one proximal wedge member 68 being disposed at the proximal end42 of the outer sleeve member 34. The proximal wedge member 68 can besized and configured to contact the proximal facing surfaces 18, 20 ofthe upper and lower body portions 14, 16 upon selective relativemovement of the proximal end 42 of the outer sleeve member 34 toward thedistal end 36 of the inner member 32. The longitudinal movement of theproximal wedge member 68 against the proximal surfaces 18, 20 can causethe separation of the upper and lower body portions 14, 16 in order tocause the intervertebral implant 10 to expand from the unexpanded stateto the expanded state, as shown in FIGS. 5 and 6 , respectively.

As illustrated in FIGS. 3-6 , the proximal wedge member 68 can be formedseparately from the outer sleeve member 34. In such an embodiment,proximal wedge member 68 can be carried on a ring or wedge-typestructure that is fitted around or over the outer sleeve member 34. Inthe illustrated embodiment, the proximal wedge member 68 can taperaxially in the distal direction. For example, as shown in FIGS. 3 and 4, the proximal wedge member 68 can have a triangle-like structure thatis disposed about the actuator shaft 30 and pushed against the proximalsurfaces 18, 20 by the collar 52 of the outer sleeve member 34.

However, in other embodiments, as shown in FIG. 8 , the proximal wedgemember 68 can also be integrally formed with and/or permanently coupledto the outer sleeve member 34. Such an embodiment can be advantageous inthat fewer parts are required, which can facilitate manufacturing anduse of the intervertebral implant 10.

Preferably, the proximal surfaces 18, 20 of the upper and lower bodyportions 14, 16 are configured to substantially match the outerconfiguration of the proximal wedge member 68. The proximal surfaces 18,20 can be integrally formed with the upper and lower body portions 14,16 and have a shape that generally tapers toward the proximal ends 22,24. The proximal surfaces 18, 20 can be defined by a smooth and constanttaper, a non-constant curve, or a contact curve, or other geometries asmay be appropriate.

For example, curvature proximal surfaces 18, 20 can be advantageousbecause initial incremental movement of the proximal wedge member 68relative to the distal end 36 of the inner member 32 can result inrelatively larger incremental distances between the upper and lower bodyportions 14, 16 than may subsequent incremental movement of the proximalwedge member 68. Thus, these types of adjustments can allow theclinician to quickly expand the intervertebral implant 10 to an initialexpanded state with few initial incremental movements, but tosubsequently expand the intervertebral implant 10 in smaller and smallerincrements in order to fine tune the placement or expanded state of theintervertebral implant 10. Thus, such embodiments can allow theefficiency of the operation to be improved and allow the clinician tofine tune the expansion of the intervertebral implant 10.

With reference to FIGS. 1 and 5 , in the illustrated embodiment, theupper and lower body portions 14, 16 can each have distally facingdistal surfaces 70, 72 disposed at distal ends 74, 76 thereof, assimilarly mentioned above with respect to the proximal surfaces 18, 20.For example, the distal surfaces 70, 72 can be inclined or otherwisecurved with respect to the longitudinal axis of the body portions 14,16. Other features, designs, and configurations of the proximal surfaces18, 20, as disclosed herein, are not repeated with respect to the distalsurfaces 70, 72, but it is understood that such features, designs, andconfigurations can similarly be incorporated into the design of thedistal surfaces 70, 72.

In such an embodiment, the actuator shaft 30 of the intervertebralimplant 10 can further comprise at least one distal wedge member 80 thatcan be disposed at the distal end 36 of the inner member 32. The distalwedge member 80 can be sized and configured to contact the distalsurfaces 70, 72 of the respective ones of the upper and lower bodyportions 14, 16 upon selective relative movement of the distal end 36 ofthe inner member 32 toward the proximal end 42 of the outer sleevemember 34. As similarly described above with respect to the proximalwedge member 68, the longitudinal movement of the distal wedge member 80against the distal surfaces 70, 72 can cause the separation of the upperand lower body portions 14, 16 thereby resulting in expansion of theintervertebral implant 10.

The description of the proximal wedge member 68 and its interaction withthe proximal surfaces 18, 20, as well as the corresponding structuresand embodiments thereof, can likewise be implemented with respect to thedistal wedge member 80 and the distal surfaces 70, 72. Therefore,discussion of alternative embodiments, structures, and functions of thedistal wedge member 80 and the distal surfaces 70, 72 need not berepeated in detail, but can include those mentioned above with respectto the distal wedge member 80 and the distal surfaces 70, 72.

In accordance with yet another embodiment illustrated in FIGS. 10A-11 ,at least one of the proximal and distal wedge members 68, 80 can beconfigured to include engagement surfaces 90, 92. The engagementsurfaces 90, 92 can include any variety of surface textures, such asridges, protrusions, and the like in order to enhance the engagementbetween the proximal and distal wedge members 68, 80 and the respectiveones of the proximal and distal surfaces 18, 20 and 70, 72. In theembodiment illustrated in FIGS. 10A-11 , the engagement surfaces 90, 92can include stepped contours 94, 96, such as comprising a plurality ofridges.

As illustrated in the detail section view of FIG. 10B, the steppedcontours 94, 96 of the engagement surfaces 90, 92 can be preferablyconfigured to be inclined or oriented obliquely with respect to the axisof the actuator shaft 30. The use of the engagement surfaces 90, 92 canpermit one-way, ratchet type longitudinal movement of proximal anddistal wedge members 68, 80 relative to the proximal and distal surfaces18, 20 and 70, 72 in order to maintain the upper and lower body portions14, 16 at a given separation distance.

Additionally, at least one of the proximal and distal surfaces 18, 20and 70, 72 of the upper and lower body portions 14, 16 can includecomplimentary engagement surfaces 100, 102, 104, 106. The complimentaryengagement surfaces 100, 102, 104, 106 can similarly include any varietyof surface textures, such as ridges, protrusions, and the like in orderto enhance the engagement between the respective ones of the distal andproximal protrusions 68, 80.

In accordance with the embodiment shown in FIGS. 10A-11 , thecomplimentary engagement surfaces 100, 102, 104, 106 can be configuredas stepped contours 108, 110 and 112, 114, such as including a pluralityof ridges. As shown best in the detail section view of FIG. 10 , thestepped contours 108, 110, 112, 114 can also be configured to beinclined or oriented obliquely with respect to the axis of the actuatorshaft 30. However, the stepped contours 108, 110, 112, 114 arepreferably inclined in a direction opposite to the stepped contours 94,96 of the proximal and distal wedge members 68, 80.

In such an embodiment, the stepped contours 108, 110, 112, 114 canengage the stepped contours 94, 96 of the wedge members 68, 80 to permitone-way ratcheting of the proximal and distal wedge members 68, 80 alongthe proximal and distal surfaces 18, 20, 70, 72. This advantageousfeature can be incorporated into various embodiments disclosed herein inorder to, inter alia, further improve the deployment and stabilizationof the intervertebral implant 10.

As shown in FIG. 10A, in this embodiment, the inner member 32 and theouter sleeve member 34 do not include complementary retention structuresas described above with reference to FIGS. 3 and 4 . Thus, in thisembodiment the inner members 32 can be moved with respect to the outersleeve member 34, and the above-described engagement between theproximal and distal wedge members 68, 80 and the respective ones of thedistal and proximal surfaces 18, 20 and 70, 72 can provide ratchet-typemovement and maintain expansion of the implant 10. However, in modifiedembodiments, the retention structures 40, 44 of the actuator shaft 30can also be provided in addition to the engagement of the proximal anddistal wedge members 68, 80 and the respective ones of the distal andproximal surfaces 18, 20 and 70, 72.

Referring again to FIGS. 3 and 4 , according to the illustratedembodiment, the intervertebral implant 10 can further comprise at leastone alignment guide 120. The alignment guide 120 can be connected to theupper and lower body portions 14, 16 and be operative to facilitateseparation of the first and second body portions 14, 16. As shown inFIGS. 3 and 4 , the alignment guide 120 can comprise a plurality ofguide rods 122 that are disposed through corresponding bores in theupper and lower body portions 14, 16. The rods 122 can be configured toorient the upper body portion 14 substantially orthogonally with respectto an axis of the actuator shaft 30 and with respect to the lower bodyportion 16. In such an embodiment, the rods 122 can each include atelescoping mechanism to enable and stabilize expansion of theintervertebral implant 30. Preferably, the alignment guide 120 alsofacilitates expansion or separation of the upper and lower body portions14, 16 in a direction substantially orthogonal to an axis of theactuator shaft 30, such as in the axial direction of the rods 122.

In accordance with another embodiment illustrated in FIGS. 12 and 13 ,the alignment guide 120 can also be configured to include a first pairof side rails 130 extending from the upper body portion 14 toward thelower body portion 16 for aligning the upper body portion 14 with thelower body portion 16 to facilitate separation of the upper and lowerbody portions 14, 16 in a direction substantially orthogonal to an axisof the actuator shaft 30. Further, the alignment guide 120 can alsoinclude a second pair of side rails 132 extending from the lower bodyportion 16 toward the upper body portion 14 for cooperating with thefirst pair of side rails 130 in aligning the upper body portion 14 withthe lower body portion 16 to facilitate separation of the upper andlower body portions 14, 16 in a direction substantially orthogonal tothe axis of the actuator shaft 30.

As shown, the first and second pairs of side rails 130, 132 can beconfigured to extend substantially orthogonally from the respective onesof the upper and lower body portions 14, 16. In this regard, althoughthe upper and lower body portions 14, 16 are illustrated as beingconfigured substantially as parallel plates, any variety ofconfigurations can be provided, such as generally ovular, wedge-shaped,and others, as mentioned above. Thus, the first and second pairs of siderails 130, 132 can be configured accordingly depending upon theconfiguration and design of the upper and lower body portions 14, 16.

For example, it is contemplated that the first and second pairs of siderails 130, 132 can be configured to ensure that the spacing between theproximal ends 22, 24 of the respective ones of the upper and lower bodyportions 14, 16 is equal to the spacing between the distal ends 74, 76thereof. However, the first and second pairs of side rails 130, 132 canalso be configured to orient exterior surfaces of the upper and lowerbody portions 14, 16 at an oblique angle relative to each other. Thus,the spacing between the proximal ends 22, 24 of the respective ones ofthe upper and lower body portions 14, 16 can be different from thespacing between the distal ends 74, 76 thereof. Thus, in one embodiment,such orientation can be created depending upon the desired configurationof the first and second pairs of side rails 130, 132.

Further, it is contemplated that the first and second pairs of siderails 130, 132 can be linear or planar in shape, as well as to generallyconform to the shape of a curve in the longitudinal direction.Furthermore, the first and second pairs of side rails 130, 132 can alsobe configured to include mating surfaces to facilitate expansion andalignment of the intervertebral implant 10. Finally, the first andsecond pairs of side rails 130, 132, although illustrated as solid, caninclude perforations or other apertures to provide circulation throughthe intervertebral space.

In accordance with yet another embodiment, a method of implanting orinstalling the spinal fusion implant 10 is also provided. The method cancomprise the steps of positioning the intervertebral implant 10 betweentwo vertebral bodies and moving the inner member 32 of the actuatorshaft 30 in an proximal direction relative to the outer sleeve member 34to force the proximal wedge member 68 and distal wedge member 80 againstthe proximal and distal surfaces 18, 20, 70, 72 of upper and lower bodyportions 14, 16 of the intervertebral implant 10 to separate the upperand lower body portions 14, 16 to cause the intervertebral implant 10 toexpand intermediate the vertebral bodies. The method can be accomplishedutilizing the various embodiments as described herein.

For any of the embodiments disclosed above, installation can besimplified through the use of the installation equipment. Theinstallation equipment can comprise a pistol grip or plier-type grip sothat the clinician can, for example, position the equipment at theproximal extension of actuator shaft 30, against the proximal end 42 ofthe outer sleeve member 34, and through one or more contractions withthe hand, the proximal end 42 of the outer sleeve member 34 and thedistal end 36 of the inner member 32 can be drawn together toappropriately tension.

In particular, while proximal traction is applied to the proximal end 38of the inner member 32, appropriate tensioning of the actuator shaft 30is accomplished by tactile feedback or through the use of a calibrationdevice for applying a predetermined load on the actuator shaft 30.Following appropriate tensioning of the actuator shaft 30, the proximalextension of the actuator shaft 30 (or the tool 50) is preferablyremoved, such as by being unscrewed, cut off or snapped off. Such a cutcan be made using conventional saws, cutters or bone forceps which areroutinely available in the clinical setting.

In certain embodiments, the proximal extension of the actuator shaft 30may be removed by cauterizing. Cauterizing the proximal extension mayadvantageously fuse the proximal end 38 of the inner member 32 to thedistal end 42 of the outer sleeve member 34, thereby adding to theretention force between the outer sleeve member 34 and the inner member30 and between the proximal and distal protrusions 68, 80 and therespective ones of the distal and proximal surfaces 18, 20 and 70, 72,if applicable. Such fusion between the proximal end 38 of the innermember 32 to the distal end 42 of the outer sleeve member 34 may beparticularly advantageous if the intervertebral implant 10 is made froma bioabsorbable and/or biodegradable material. In this manner, as thematerial of the proximal anchor and/or the actuator shaft is absorbed ordegrades, the fusion caused by the cauterizing continues to provideretention force between the proximal anchor and the pin.

Following trimming the proximal end of actuator shaft 30, the accesssite may be closed and dressed in accordance with conventional woundclosure techniques.

Preferably, the clinician will have access to an array of intervertebralimplants 10, having different widths and axial lengths. These may bepackaged one or more per package in sterile envelopes or peelablepouches. Upon encountering an intervertebral space for which the use ofa intervertebral implant 10 is deemed appropriate, the clinician willassess the dimensions and load requirements of the spine 12, and selectan intervertebral implant 10 from the array which meets the desiredspecifications.

The embodiments described above may be used in other anatomical settingsbeside the spine. As mentioned above, the embodiments described hereinmay be used for spinal fixation. In embodiments optimized for spinalfixation in an adult human population, the upper and lower portions 14,15 will generally be within the range of from about 10-60 mm in lengthand within the range of from about 5-30 mm in maximum width and thedevice can expand from a height of about 5 mm to about 30 mm.

For the embodiments discussed herein, the intervertebral implantcomponents can be manufactured in accordance with any of a variety oftechniques which are well known in the art, using any of a variety ofmedical-grade construction materials. For example, the upper and lowerbody portions 14, 16, the actuator shaft 30, and other components can beinjection-molded from a variety of medical-grade polymers including highor other density polyethylene, PEEK™ polymers, nylon and polypropylene.Retention structures 40, 44 can also be integrally molded with theactuator shaft 30. Alternatively, retention structures 40, 44 can bemachined or pressed into the actuator shaft 30 in a post-moldingoperation, or secured using other techniques depending upon theparticular design. The retention structures 40, 44 can also be made of adifferent material.

The intervertebral implant 10 components can be molded, formed ormachined from biocompatible metals such as Nitinol, stainless steel,titanium, and others known in the art. Non-metal materials such asplastics, PEEK™ polymers, and rubbers can also be used. Further, theimplant components can be made of combinations of PEEK™ polymers andmetals. In one embodiment, the intervertebral implant components can beinjection-molded from a bioabsorbable material, to eliminate the needfor a post-healing removal step.

The intervertebral implant components may contain one or more bioactivesubstances, such as antibiotics, chemotherapeutic substances, angiogenicgrowth factors, substances for accelerating the healing of the wound,growth hormones, antithrombogenic agents, bone growth accelerators oragents, and the like. Such bioactive implants may be desirable becausethey contribute to the healing of the injury in addition to providingmechanical support.

In addition, the intervertebral implant components may be provided withany of a variety of structural modifications to accomplish variousobjectives, such as osteoincorporation, or more rapid or uniformabsorption into the body. For example, osteoincorporation may beenhanced by providing a micropitted or otherwise textured surface on theintervertebral implant components. Alternatively, capillary pathways maybe provided throughout the intervertebral implant, such as bymanufacturing the intervertebral implant components from an open cellfoam material, which produces tortuous pathways through the device. Thisconstruction increases the surface area of the device which is exposedto body fluids, thereby generally increasing the absorption rate.Capillary pathways may alternatively be provided by laser drilling orother technique, which will be understood by those of skill in the artin view of the disclosure herein. Additionally, apertures can beprovided in the implant to facilitate packing of biologics into theimplant, backfilling, and/or osseointegration of the implant. Ingeneral, the extent to which the intervertebral implant can be permeatedby capillary pathways or open cell foam passageways may be determined bybalancing the desired structural integrity of the device with thedesired reabsorption time, taking into account the particular strengthand absorption characteristics of the desired polymer.

The intervertebral implant may be sterilized by any of the well knownsterilization techniques, depending on the type of material. Suitablesterilization techniques include heat sterilization, radiationsterilization, such as cobalt irradiation or electron beams, ethyleneoxide sterilization, and the like.

Referring now to FIGS. 14A-14D, various modified configurations andapplications of the implant are illustrated. As mentioned above, theembodiments, applications, and arrangements disclosed herein can bereadily modified by one of skill in order to suit the requirements ofthe clinician. It will therefore be appreciated that embodimentsdisclosed herein are not limited to those illustrated, but can becombined and/or modified.

FIG. 14A is a side view of another embodiment of an intervertebralimplant 10 wherein the upper and lower body portions 14, 16 havegenerally slanted configurations. As illustrated, the upper and lowerbody portions 14, 16 can define generally convex upper and lowersurfaces 140, 142, respectively. Such an embodiment can be beneficialespecially in applications where the implant 10 must complement thenatural curvature of the spine. The upper and lower surfaces 140, 142can generally match the concavity of adjacent upper and lower vertebralbodies. It will be appreciated that the slanted configuration can bemodified and a range of curvatures can be accommodated as required.Furthermore, the upper and lower surfaces 140, 142 can be generallyplanar and oriented at an angle relative to each other. In someembodiments, the upper and lower surfaces 140, 142 of the implant 10 canbe formed such that the implant defines a generally wedge-shaped design.The dimensions of the implant 10 can be varied as desired.

As illustrated in FIG. 14A, the upper and lower body portions 14, 16 canbe configured such that exterior surfaces thereof are oriented obliquelywith respect to interior surfaces thereof. For example, in someembodiments, the upper and lower body portions 14, 16 can be configuredgenerally as wedges. However, as also mentioned with regard to FIGS. 12and 13 , it is also contemplated that the actuation mechanism of theimplant can allow the spacing between the proximal ends of therespective ones of the upper and lower body portions to be differentfrom of the spacing between the distal ends thereof due to the overallconfiguration of the implant.

In this regard, the angular relationship between the upper and lowerbody portions 14, 16 can be varied as desired. For example, the spacingof the distal ends of the upper and lower body portions 14, 16 canincrease at a greater rate as the implant is expanded that the spacingbetween the proximal ends of the upper and lower body portions 14, 16,or vice versa. This feature can result from the interaction of theactuator shaft with the implant, the wedges with the upper and lowerbody portions 14, 16, or the actuator shaft with the wedges. It iscontemplated, for example, that the distal and proximal wedges can havedifferent configurations with different angular relationships betweentheir contact surfaces. Further, the actuator shaft can have differentthread configurations such that one wedge advances faster than the otherwedge upon rotation of the pin. Alternative embodiments can also bedeveloped based on the present disclosure.

Referring now to FIG. 14B, a top view of another embodiment of anintervertebral implant 10 is provided wherein the implant 10 has agenerally clamshell configuration. Such an embodiment can be beneficialin applications where the clinician desires to support the vertebraeprincipally about their peripheral aspects.

For example, at least one of the upper and lower body portions 14, 16can be configured to have a semicircular face. When such an embodimentis implanted and deployed in a patient, the outwardly bowed portions ofthe upper and lower body portions 14, 16 provide a footprint that allowsthe implant 10 to contact the vertebrae about their periphery, asopposed to merely supporting the vertebrae in a substantially central oraxial location. In such embodiments, the upper and lower body portions14, 16 can thus be banana or crescent shaped to facilitate contact withcortical bone. Thus, such embodiments can employ the more durable,harder structure of the periphery of the vertebrae to support the spine.

In an additional embodiment, FIG. 14C shows a top view of anintervertebral implant 10 illustrating that the implant 10 can have agenerally square configuration and footprint when implanted into theintervertebral space of the spine 12. Such a configuration would likelybe utilized in a more invasive procedure, rather than in percutaneousapplications. As mentioned above with respect to FIG. 14B, the footprintof such an embodiment can allow the implant 10 to more fully contact themore durable, harder portions of the vertebrae to facilitate support andhealing of the spine. Alternative embodiments can be created thatprovide ovular, circular, hexagonal, rectangular, and any other shapedfootprint.

Furthermore, FIG. 14D is a top view of the spine 12 illustrating anexemplary application of the intervertebral implant. In this example, aplurality of intervertebral implants 10′ and 10″ (shown in hidden lines)can be disposed in an intervertebral space of the spine 12 to supportadjacent vertebrae. As mentioned above, one of the beneficial aspects ofembodiments of the implant provides that the implant can be used inpercutaneous applications.

In FIG. 14D, it is illustrated that one or more implants 10′ can beimplanted and oriented substantially parallel with respect to each otherin order to support the adjacent vertebrae. Also shown, at least twoimplants 10″ can be implanted and oriented transversely with respect toeach other in order to support the adjacent vertebrae. In addition, itis contemplated that a cross-midline approach can be used wherein asingle implant is placed into the intervertebral space in an orientationas depicted for one of the implants 10′, although more centrally. Thus,the angular orientation of the implant(s) can be varied. Further, thenumber of implants used in the spinal fusion procedure can also bevaried to include one or more. Other such configurations, orientations,and operational parameters are contemplated in order to aid theclinician in ensuring that the adjacent vertebrae are properlysupported, and that such procedure is performed in a minimally invasivemanner.

Referring now to FIG. 15 , yet another embodiment is provided. FIG. 15is a side view of an intervertebral implant 10 in an unexpanded state inwhich a screw mechanism 150 can be utilized to draw the proximal anddistal wedged members 68, 80 together to cause the implant to move to anexpanded state. Thus, a rotational motion, instead of a translationalmotion (as discussed above in reference to other embodiments) can beutilized to cause the implant 10 to move to its expanded state.

In some embodiments, the screw mechanism 150 can comprise an Archimedesscrew, a jack bolt, or other fastener that can cause the convergence oftwo elements that are axially coupled to the fastener. The screwmechanism 150 can have at least one thread disposed along at least aportion thereof, if not along the entire length thereof. Further, thescrew mechanism can be threadably attached to one or both of theproximal and distal wedge members 68, 80. As illustrated in FIG. 15 ,the distal wedge member 80 can also be freely rotatably attached to thescrew mechanism 150 while the proximal wedge member 68 is threadablyattached thereto. Further, as disclosed above with respect to the pin,the screw mechanism 150 can also be configured such that a proximalportion of the screw mechanism 150 can be removed after the implant 10has been expanded in order to eliminate any proximal protrusion of thescrew mechanism 150.

Therefore, in the illustrated embodiment, it is contemplated that uponrotation of the screw mechanism 150, the proximal and distal wedgedmembers 68, 80 can be axially drawn closer together. As a result of thisaxial translation, the proximal and distal wedged members 68, 80 cancontact the respective ones of the proximal and distal surfaces 18, 20and 70, 72 in order to facilitate separation of the upper and lower bodyportions 14, 16, as similarly disclosed above.

The screw mechanism 150 can be utilized to provide a stabilizing axialforce to the proximal and distal wedge members 68, 80 in order tomaintain the expansion of the implant 10. However, it is alsocontemplated that other features can be incorporated into such anembodiment to facilitate the maintenance of the expansion. In thisregard, although the axial force provided by the screw mechanism 150 cantend to maintain the position and stability of the proximal and distalwedge members 68, 80, additional features can be employed to ensure thestrength and stability of the implant 10 when in its expanded state.

For example, as discussed above with respect to FIGS. 10A-10B, theproximal and distal wedge members 68, 80 can include engagement surfaces90, 92, such as stepped contours 94, 96. As discussed above, the use ofthe engagement surfaces 90, 92 can permit one-way, ratchet typelongitudinal movement of proximal and distal wedge members 68, 80relative to the proximal and distal surfaces 18, 20 and 70, 72 in orderto maintain the upper and lower body portions 14, 16 at a givenseparation distance.

Furthermore, as also disclosed above, at least one of the proximal anddistal surfaces 18, 20 and 70, 72 of the upper and lower body portions14, 16 can include complimentary engagement surfaces 100, 102, 104, 106to enhance the engagement between the respective ones of the distal andproximal protrusions 68, 80. In an embodiment, the complimentaryengagement surfaces 100, 102, 104, 106 can be configured as steppedcontours 108, 110 and 112, 114. Thus, the stepped contours 108, 110,112, 114 can engage the stepped contours 94, 96 of the wedge members 68,80 to permit one-way ratcheting of the proximal and distal wedge members68, 80 along the proximal and distal surfaces 18, 20, 70, 72.

Therefore, some embodiments can be configured such that a rotationalmotion can be exerted on the actuator shaft or screw mechanism, insteadof a pulling or translational motion, in order to expand an embodimentof the implant from an unexpanded state (such as that illustrated inFIG. 12 ) to an expanded state (such as that illustrated in FIG. 13 ).Such embodiments can be advantageous in certain clinical conditions andcan provide the clinician with a variety of options for the benefit ofthe patient. Further, the various advantageous features discussed hereinwith respect to other embodiments can also be incorporated into suchembodiments.

Referring now to FIG. 16A-19 , another embodiment of the implant isillustrated. FIG. 16A is a perspective view of an intervertebral implant200 in an unexpanded state. The implant 200 can comprise upper and lowerbody portions 202, 204, proximal and distal wedge members 206, 208, andan actuator shaft 210. In the unexpanded state, the upper and lower bodyportions 202, 204 can be generally abutting with a height of the implant200 being minimized. However, the implant 200 can be expanded, as shownin FIG. 16B to increase the height of the implant 200 when implantedinto the intervertebral space of the spine.

In some embodiments, the height of the implant 200 can be betweenapproximately 7-15 mm, and more preferably, between approximately 8-13mm. The width of the implant can be between approximately 7-11 mm, andpreferably approximately 9 mm. The length of the implant 200 can bebetween approximately 18-30 mm, and preferably approximately 22 mm.Thus, the implant 200 can have a preferred aspect ratio of betweenapproximately 7:11 and 15:7, and preferably approximately between 8:9and 13:9. It is contemplated that various modifications to the dimensiondisclosed herein can be made by one of skill and the mentioneddimensions shall not be construed as limiting.

Additionally, as noted above, the implant 200 can also be made usingnon-metal materials such as plastics, PEEK™ polymers, and rubbers.Further, the implant components can be made of combinations of PEEK™polymers and metals. Accordingly, the implant 200 can be at leastpartially radiolucent, which radiolucency can allow a doctor to perceivethe degree of bone growth around and through the implant. The individualcomponents of the implant 200 can be fabricated of such materials basedon needed structural, biological and optical properties.

As discussed generally above with respect to FIG. 15 , it iscontemplated that the actuator shaft 210 can be rotated to cause theproximal and distal wedge members to move toward each other, thuscausing the upper and lower body portions 202, 204 to be separated.Although, the present embodiment is illustrated using this mode ofexpansion, it is contemplated that other modes of expansion describedabove (e.g., one way-ratchet type mechanism) can be combined with orinterchanged herewith.

In some embodiments, the implant 200 can be configured such that theproximal and distal wedge members 206, 208 are interlinked with theupper and lower body portions 202, 204 to improve the stability andalignment of the implant 200. For example, the upper and lower bodyportions 202, 204 can be configured to include slots (slot 220 is shownin FIG. 16A, and slots 220, 222 are shown in FIG. 16B; the configurationof such an embodiment of the upper and lower body portions 202, 204 isalso shown in FIGS. 20A-21B, discussed below). In such an embodiment,the proximal and distal wedge members 206, 208 can be configured toinclude at least one guide member (an upper guide member 230 of theproximal wedge member 206 is shown in FIG. 16A and an upper guide member232 of the distal wedge member 208 is shown in FIG. 18 ) that at leastpartially extends into a respective slot of the upper and lower bodyportions. The arrangement of the slots and the guide members can enhancethe structural stability and alignment of the implant 200.

In addition, it is contemplated that some embodiments of the implant 200can be configured such that the upper and lower body portions 202, 204each include side portions (shown as upper side portion 240 of the upperbody portion 202 and lower side portion 242 of the lower body portion204) that project therefrom and facilitate the alignment,interconnection, and stability of the components of the implant 200.FIG. 16B is a perspective view of the implant 200 wherein the implant200 is in the expanded state. The upper and lower side portions 240, 242can be configured to have complementary structures that enable the upperand lower body portions 202, 204 to move in a vertical direction.Further, the complementary structures can ensure that the proximal endsof the upper and lower body portions 202, 204 generally maintain spacingequal to that of the distal ends of the upper and lower body portions202, 204. The complementary structures are discussed further below withregard to FIGS. 17-21B.

Furthermore, as described further below, the complementary structurescan also include motion limiting portions that prevent expansion of theimplant beyond a certain height. This feature can also tend to ensurethat the implant is stable and does not disassemble during use.

In some embodiments, the actuator shaft 210 can facilitate expansion ofthe implant 200 through rotation, longitudinal contract of the pin, orother mechanisms. The actuator shaft 210 can include threads thatthreadably engage at least one of the proximal and distal wedge members206, 208. The actuator shaft 210 can also facilitate expansion throughlongitudinal contraction of the actuator shaft as proximal and distalcollars disposed on inner and outer sleeves move closer to each other toin turn move the proximal and distal wedge members closer together, asdescribed above with respect to actuator shaft 30 shown in FIGS. 5-6 .It is contemplated that in other embodiments, at least a portion of theactuator shaft can be axially fixed relative to one of the proximal anddistal wedge members 206, 208 with the actuator shaft being operative tomove the other one of the proximal and distal wedge members 206, 208 viarotational movement or longitudinal contraction of the pin.

Further, in embodiments wherein the actuator shaft 210 is threaded, itis contemplated that the actuator shaft 210 can be configured to bringthe proximal and distal wedge members closer together at differentrates. In such embodiments, the implant 200 could be expanded to aV-configuration or wedged shape. For example, the actuator shaft 210 cancomprise a variable pitch thread that causes longitudinal advancement ofthe distal and proximal wedge members at different rates. Theadvancement of one of the wedge members at a faster rate than the othercould cause one end of the implant to expand more rapidly and thereforehave a different height that the other end. Such a configuration can beadvantageous depending on the intervertebral geometry and circumstantialneeds.

In other embodiments, the implant 200 can be configured to includeanti-torque structures 250. The anti-torque structures 250 can interactwith at least a portion of a deployment tool during deployment of theimplant to ensure that the implant maintains its desired orientation(see FIGS. 25-26 and related discussion). For example, when the implant200 is being deployed and a rotational force is exerted on the actuatorshaft 210, the anti-torque structures 250 can be engaged by anon-rotating structure of the deployment tool to maintain the rotationalorientation of the implant 200 while the actuator shaft 210 is rotated.The anti-torque structures 250 can comprise one or more inwardlyextending holes or indentations on the proximal wedge member 206, whichare shown as a pair of holes in FIGS. 16A-B. However, the anti-torquestructures 250 can also comprise one or more outwardly extendingstructures.

According to yet other embodiments, the implant 200 can be configured toinclude one or more apertures 252 to facilitate osseointegration of theimplant 200 within the intervertebral space. As mentioned above, theimplant 200 may contain one or more bioactive substances, such asantibiotics, chemotherapeutic substances, angiogenic growth factors,substances for accelerating the healing of the wound, growth hormones,antithrombogenic agents, bone growth accelerators or agents, and thelike. Indeed, various biologics can be used with the implant 200 and canbe inserted into the disc space or inserted along with the implant 200.The apertures 252 can facilitate circulation and bone growth throughoutthe intervertebral space and through the implant 200. In suchimplementations, the apertures 252 can thereby allow bone growth throughthe implant 200 and integration of the implant 200 with the surroundingmaterials.

FIG. 17 is a bottom view of the implant 200 shown in FIG. 16A. As showntherein, the implant 200 can comprise one or more protrusions 260 on abottom surface 262 of the lower body portion 204. Although not shown inthis FIG., the upper body portion 204 can also define a top surfacehaving one or more protrusions thereon. The protrusions 260 can allowthe implant 200 to engage the adjacent vertebrae when the implant 200 isexpanded to ensure that the implant 200 maintains a desired position inthe intervertebral space.

The protrusions 260 can be configured in various patterns. As shown, theprotrusions 260 can be formed from grooves extending widthwise along thebottom surface 262 of the implant 200 (also shown extending from a topsurface 264 of the upper body portion 202 of the implant 200). Theprotrusions 260 can become increasingly narrow and pointed toward theirapex. However, it is contemplated that the protrusions 260 can be one ormore raised points, cross-wise ridges, or the like.

FIG. 17 also illustrates a bottom view of the profile of an embodimentof the upper side portion 240 and the profile of the lower side portion242. As mentioned above, the upper and lower side portions 240, 242 caneach include complementary structures to facilitate the alignment,interconnection, and stability of the components of the implant 200.FIG. 17 also shows that in some embodiments, having a pair of each ofupper and lower side portions 240, 242 can ensure that the upper andlower body portions 202, 204 do not translate relative to each other,thus further ensuring the stability of the implant 200.

As illustrated in FIG. 17 , the upper side portion 240 can comprise agroove 266 and the lower side portion can comprise a rib 268 configuredto generally mate with the groove 266. The groove 266 and rib 268 canensure that the axial position of the upper body portion 202 ismaintained generally constant relative to the lower body portion 204.Further, in this embodiment, the grooves 266 and rib 268 can also ensurethat the proximal ends of the upper and lower body portions 202, 204generally maintain spacing equal to that of the distal ends of the upperand lower body portions 202, 204. This configuration is alsoillustratively shown in FIG. 18 .

Referring again to FIG. 17 , the implant 200 is illustrated in theunexpanded state with each of the respective slots 222 of the lower bodyportion 204 and lower guide members 270, 272 of the respective ones ofthe proximal and distal wedge members 206, 208. In some embodiments, asshown in FIGS. 16A-17 and 19-21B, the slots and guide members can beconfigured to incorporate a generally dovetail shape. Thus, once a givenguide member is slid into engagement with a slot, the guide member canonly slide longitudinally within the slot and not vertically from theslot. This arrangement can ensure that the proximal and distal wedgemembers 206, 208 are securely engaged with the upper and lower bodyportions 202, 204.

Furthermore, in FIG. 18 , a side view of the embodiment of the implant200 in the expanded state illustrates the angular relationship of theproximal and distal wedge members 206, 208 and the upper and lower bodyportions 202, 204. As mentioned above, the dovetail shape of the slotsand guide members ensures that for each given slot and guide member, agiven wedge member is generally interlocked with the give slot to onlyprovide one degree of freedom of movement of the guide member, and thusthe wedge member, in the longitudinal direction of the given slot.

Accordingly, in such an embodiment, the wedge members 206, 208 may notbe separable from the implant when the implant 200 is in the unexpandedstate (as shown in FIG. 16A) due to the geometric constraints of theangular orientation of the slots and guide members with the actuatorshaft inhibiting longitudinal relative movement of the wedge members206, 208 relative to the upper and lower body portions 202, 204. Such aconfiguration ensures that the implant 200 is stable and structurallysound when in the unexpanded state or during expansion thereof, thusfacilitating insertion and deployment of the implant 200.

Such an embodiment of the implant 200 can therefore be assembled byplacing or engaging the wedge members 206, 208 with the actuator shaft210, moving the wedge members 206, 208 axially together, and insertingthe upper guide members 230, 232 into the slots 220 of the upper bodyportion 202 and the lower guide members 270, 272 into the slots 222 ofthe lower body portion 204. The wedge members 206, 208 can then be movedapart, which movement can cause the guide members and slots to engageand bring the upper and lower body portions toward each other. Theimplant 200 can then be prepared for insertion and deployment byreducing the implant 200 to the unexpanded state.

During assembly of the implant 200, the upper and lower body portions202, 204 can be configured to snap together to limit expansion of theimplant 200. For example, the upper and lower side portions 240, 242 cancomprise upper and lower motion-limiting structures 280, 282, as shownin the cross-sectional view of FIG. 19 . After the wedge members 206,208 are engaged with the upper and lower body portions 202, 204 andaxially separated to bring the upper and lower body portions 202, 204together, the upper motion-limiting structure 280 can engage the lowermotion-limiting structure 282. This engagement can occur due todeflection of at least one of the upper and lower side portions 240,242. However, the motion-limiting structures 280, 282 preferablycomprise interlocking lips or shoulders to engage one another when theimplant 200 has reached maximum expansion. Accordingly, after the wedgemembers 206, 208 are assembled with the upper and lower body portions202, 204, these components can be securely interconnected to therebyform a stable implant 200.

Referring again to FIG. 18 , the implant 200 can define generally convextop and bottom surfaces 264, 262. This shape, as discussed above withrespect to FIG. 14A, can be configured to generally match the concavityof adjacent vertebral bodies.

FIGS. 20A-B illustrate perspective views of the lower body portion 204of the implant 200, according to an embodiment. These FIGS. provideadditional clarity as to the configuration of the slots 222, the lowerside portions 242, and the lower motion-limiting members 282 of thelower body portion 204. Similarly, FIGS. 21A-B illustrate perspectiveviews of the upper body portion 202 of the implant 200, according to anembodiment. These FIGS. provide additional clarity as to theconfiguration of the slots 220, the upper side portions 240, and theupper motion-limiting members 280 of the upper body portion 202.Additionally, the upper and lower body portions 202, 204 can also definea central receptacle 290 wherein the actuator shaft can be received.Further, as mentioned above, the upper and lower body portions 202, 204can define one or more apertures 252 to facilitate osseointegration.

FIG. 22 is a perspective view of an actuator shaft 210 of the implant200 shown in FIG. 16A. In this embodiment, the actuator shaft 210 can bea single, continuous component having threads 294 disposed thereon forengaging the proximal and distal wedge members 206, 208. The threads canbe configured to be left hand threads at a distal end of the actuatorshaft 210 and right hand threads at a proximal other end of the actuatorshaft for engaging the respective ones of the distal and proximal wedgemembers 208, 206. Accordingly, upon rotation of the actuator shaft 210,the wedge members 206, 208 can be caused to move toward or away fromeach other to facilitate expansion or contraction of the implant 200.Further, as noted above, although this embodiment is described andillustrated as having the actuator shaft 210 with threads 294, it isalso contemplated that relative movement of the wedge members can beachieved through the use of the actuator shaft 30 described in referenceto FIGS. 5-6 , and that such an actuator shaft could likewise be usedwith the embodiment shown in FIGS. 16A-19 .

In accordance with an embodiment, the actuator shaft 210 can alsocomprise a tool engagement section 296 and a proximal engagement section298. The tool engagement section 296 can be configured as a to beengaged by a tool, as described further below. The tool engagementsection 296 can be shaped as a polygon, such as a hex shape. As shown,the tool engagement section 296 is star shaped and includes six points,which configuration tends to facilitate the transfer of torque to theactuator shaft 210 from the tool. Other shapes and configurations canalso be used.

Furthermore, the proximal engagement section 298 of the actuator shaft210 can comprise a threaded aperture. The threaded aperture can be usedto engage a portion of the tool for temporarily connecting the tool tothe implant 200. It is also contemplated that the proximal engagementsection 298 can also engage with the tool via a snap or press fit.

FIG. 23A-B illustrate perspective views of the proximal wedge member 206of the implant 200. As described above, the proximal wedge member caninclude one or more anti-torque structures 250. Further, the guidemembers 230, 270 are also illustrated. The proximal wedge member 206 cancomprise a central aperture 300 where through an actuator shaft can bereceived. When actuator shaft 210 is used in an embodiment, the centralaperture 300 can be threaded to correspond to the threads 294 of theactuator shaft 210. In other embodiments, the actuator shaft can engageother portions of the wedge member 206 for causing expansion orcontraction thereof.

FIG. 24A-B illustrate perspective views of the distal wedge member 208of the implant 200. As similarly discussed above with respect to theproximal wedge member 206, the guide members 232, 272 and a centralaperture 302 of the proximal wedge member 206 are illustrated. Thecentral aperture 302 can be configured to receive an actuator shafttherethrough. When actuator shaft 210 is used in an embodiment, thecentral aperture 302 can be threaded to correspond to the threads 294 ofthe actuator shaft 210. In other embodiments, the actuator shaft canengage other portions of the wedge member 208 for causing expansion orcontraction thereof.

Referring now to FIG. 25 , there is illustrated a perspective view of adeployment tool 400 according to another embodiment. The tool 400 cancomprise a handle section 402 and a distal engagement section 404. Thehandle portion 402 can be configured to be held by a user and cancomprise various features to facilitate implantation and deployment ofthe implant.

According to an embodiment, the handle section 402 can comprise a fixedportion 410, and one or more rotatable portions, such as the rotatabledeployment portion 412 and the rotatable tethering portion 414. In suchan embodiment, the tethering portion 414 can be used to attach theimplant to the tool 400 prior to insertion and deployment. Thedeployment portion 412 can be used to actuate the implant and rotate theactuator shaft thereof for expanding the implant. Then, after theimplant is expanded and properly placed, the tethering portion 414 canagain be used to untether or decouple the implant from the tool 400.

Further, the distal engagement section 404 can comprise a fixed portion420, an anti-torque component 422, a tethering rod (element 424 shown inFIG. 26 ), and a shaft actuator rod (element 426 shown in FIG. 26 ) tofacilitate engagement with and actuation of the implant 200. Theanti-torque component 422 can be coupled to the fixed portion 420. Asdescribed above with reference to FIGS. 16A-B, in an embodiment, theimplant 200 can comprise one or more anti-torque structures 250. Theanti-torque component 422 can comprise one or more protrusions thatengage the anti-torque structures 250 to prevent movement of the implant200 when a rotational force is applied to the actuator shaft 210 via thetool 400. As illustrated, the anti-torque component 422 can comprise apair of pins that extend from a distal end of the tool 400. However, itis contemplated that the implant 200 and tool 400 can be variouslyconfigured such that the anti-torque structures 250 and the anti-torquecomponent 422 interconnect to prevent a torque being transferred to theimplant 200. The generation of the rotational force will be explained ingreater detail below with reference to FIG. 26 , which is a side-crosssectional view of the tool 400 illustrating the interrelationship of thecomponents of the handle section 402 and the distal engagement section404.

For example, as illustrated in FIG. 26 , the fixed portion 410 of thehandle section 402 can be interconnected with the fixed portion 420 ofthe distal engagement section 404. The distal engagement section 404 canbe configured with the deployment portion 412 being coupled with theshaft actuator rod 426 and the tethering portion 414 being coupled withthe tethering rod 424. Although these portions can be coupled to eachother respectively, they can move independently of each other andindependently of the fixed portions. Thus, while holding the fixedportion 410 of the handle section 402, the deployment portion 412 andthe tethering portion 414 can be moved to selectively expand or contractthe implant or to attach the implant to the tool, respectively. In theillustrated embodiment, these portions 412, 414 can be rotated to causerotation of an actuator shaft 210 of an implant 200 engaged with thetool 400.

As shown in FIG. 26 , the tether rod 424 can comprise a distalengagement member 430 being configured to engage a proximal end of theactuator shaft 210 of the implant 200 for rotating the actuator shaft210 to thereby expand the implant from an unexpanded state to andexpanded state. The tether rod 424 can be configured with the distalengagement member 430 being a threaded distal section of the rod 424that can be threadably coupled to an interior threaded portion of theactuator shaft 210.

In some embodiments, the tool 400 can be prepared for a single-use andcan be packaged with an implant preloaded onto the tool 400. Thisarrangement can facilitate the use of the implant and also provide asterile implant and tool for an operation. Thus, the tool 400 can bedisposable after use in deploying the implant.

Referring again to FIG. 25 , an embodiment of the tool 400 can alsocomprise an expansion indicator gauge 440 and a reset button 450. Theexpansion indicator gauge 440 can be configured to provide a visualindication corresponding to the expansion of the implant 200. Forexample, the gauge 440 can illustrate an exact height of the implant 200as it is expanded or the amount of expansion. As shown in FIG. 26 , thetool 400 can comprise a centrally disposed slider element 452 that canbe in threaded engagement with a thread component 454 coupled to thedeployment portion 412.

In an embodiment, the slider element 452 and an internal cavity 456 ofthe tool can be configured such that the slider element 452 is providedonly translational movement in the longitudinal direction of the tool400. Accordingly, as the deployment portion 412 is rotated, the threadcomponent 454 is also rotated. In such an embodiment, as the threadcomponent 454 rotates and is in engagement with the slider component452, the slider element 452 can be incrementally moved from an initialposition within the cavity 456 in response to the rotation of thedeployment portion 412. An indicator 458 can thus be longitudinallymoved and viewed to allow the gauge 440 to visually indicate theexpansion and/or height of the implant 200. In such an embodiment, thegauge 440 can comprises a transparent window through which the indicator458 on the slider element 452 can be seen. In the illustratedembodiment, the indicator 458 can be a marking on an exterior surface ofthe slider element 452.

In embodiments where the tool 400 can be reused, the reset button 450can be utilized to zero out the gauge 440 to a pre-expansion setting. Insuch an embodiment, the slider element 452 can be spring-loaded, asshown with the spring 460 in FIG. 26 . The reset button 450 candisengage the slider element 452 and the thread component 454 to allowthe slider element 452 to be forced back to the initial position.

The specific dimensions of any of the embodiment disclosed herein can bereadily varied depending upon the intended application, as will beapparent to those of skill in the art in view of the disclosure herein.Moreover, although the present inventions have been described in termsof certain preferred embodiments, other embodiments of the inventionsincluding variations in the number of parts, dimensions, configurationand materials will be apparent to those of skill in the art in view ofthe disclosure herein. In addition, all features discussed in connectionwith any one embodiment herein can be readily adapted for use in otherembodiments herein to form various combinations and sub-combinations.The use of different terms or reference numerals for similar features indifferent embodiments does not imply differences other than those whichmay be expressly set forth. Accordingly, the present inventions areintended to be described solely by reference to the appended claims, andnot limited to the preferred embodiments disclosed herein.

What is claimed is:
 1. A method of implanting an expandableintervertebral implant comprising: positioning the implant between twovertebral bodies via a transforaminal approach, wherein the implantcomprises: an upper body portion having respective first and secondsloped surfaces, and a lower body portion having respective first andsecond sloped surfaces, wherein the upper and lower body portions areone-piece structures from their respective first sloped surfaces totheir respective second sloped surfaces; an actuator shaft receivedbetween the upper and lower body portions, the actuator shaft comprisingan inner member and an outer sleeve member, the inner member having arespective first end and a respective second end spaced from therespective first end in a first direction, the outer sleeve memberhaving a respective first end and a respective second end spaced fromthe respective first end of the outer sleeve member in the firstdirection, wherein the outer sleeve member is threadedly coupled to theinner member such that rotation of the inner member relative to theouter sleeve member causes a reduction of a first longitudinal distancefrom the first end of the outer sleeve member to the second end of theinner member along a longitudinal direction that includes the firstdirection and a second direction opposite the first direction; a firstwedge member supported by the outer sleeve member, wherein the firstwedge member spans a second longitudinal distance along the longitudinaldirection, and the outer sleeve member extends out with respect to thefirst wedge member in the first direction a respective distance that isgreater than the second longitudinal distance; and a second wedge membersupported by the inner member at a location spaced from the first wedgemember in the first direction; and after the positioning step, rotatingthe inner member relative to the outer sleeve member so as to reduce arespective distance between the first wedge member and the second wedgemember along the longitudinal direction, thereby forcing the first wedgemember against the first sloped surfaces of the upper and lower bodyportions, and forcing the second wedge member against the second slopedsurfaces of the upper and lower body portions, thereby expanding theimplant to an expanded position.
 2. The method of claim 1, wherein thefirst wedge member remains longitudinally fixed with respect to theouter sleeve member during the rotating step, and the second wedgemember remains longitudinally fixed with respect to the inner memberduring the rotating step.
 3. The method of claim 2, wherein the secondwedge member is disposed at the second end of the inner member.
 4. Themethod of claim 3, wherein the first wedge member is disposed at thefirst end of the outer sleeve member.
 5. The method of claim 2, whereinthe second end of the outer member defines a lumen that threadedlyreceives the inner member in the second direction, and the rotating stepcomprises advancing the first end of the inner member into the lumen inthe second direction.
 6. The method of claim 1, wherein the first wedgemember is disposed at the first end of the outer sleeve member, and thesecond wedge member is disposed at the second end of the inner member.7. The method of claim 1, further comprising the step of maintaining theimplant in the expanded position while the first and second wedgemembers are in contact with the respective first and second slopedsurfaces of the upper and lower body portions.
 8. The method of claim 1,wherein the rotating step causes an alignment projection to ride in analignment opening of the upper body portion, thereby restrictingmovement of the upper body portion relative to the lower body portion toa direction substantially perpendicular to the longitudinal direction.9. The method of claim 1, wherein the implant further comprises arespective alignment guide extending into each of the upper and lowerbody portions.
 10. The method of claim 9, wherein the alignment guiderestricts the expanding of the implant to occur in a directionsubstantially orthogonal to an axis of the actuator shaft.
 11. Themethod of claim 1, wherein the rotating step causes an alignmentprojection to ride in an alignment opening of the upper body portion,thereby restricting movement of the upper body portion relative to thelower body portion to a direction substantially perpendicular to thelongitudinal direction as the implant expands to the expanded position.12. The method of claim 1, further comprising an alignment guide thatextends into respective alignment openings of the upper and lower bodyportions, such that the rotating step causes the alignment guide to ridein an alignment openings, thereby restricting relative movement of theupper and lower body portions as the implant expands to the expandedposition.
 13. The method of claim 1, wherein the portion of the outersleeve member extends out from the first wedge member to the second endof the outer sleeve member in the first direction.
 14. The method ofclaim 1, wherein the first and second sloped surfaces are at respectiveends of the upper and lower body portions that are opposite each otheralong the longitudinal direction.